Discuss The Viv Lab Rigid Arm

@intactaudio : " for some reason you introduced this particular tangent in response to me simply mentioning in order to get two null points both overhang and offset are required. "

Yes the VIV issue is useless for me but I return here because you posted totally wrong about tonearm alignment. All your statements about are totally false and Agon threads are reading for several audiophiles that can’t " learn " from you wat’s ( again ) a FALSE information.

In the last 80+ years no one never questioned Löfgren A equations, NO ONE but you. Go figure ! . and from your posts you not even make the calculation using the Löfgren equation I linked, incredible  ! ! !  you follow posting about.

Yes, I did it.  Btw, any one of you already did it using IEC standard?

Now it’s really enough on the alignment issue where no one needs overhang/off-set angle to determine null points, only needs most inner/outer radius exactly as Löfgreen stated 80+ years agoin the linked formula.

R.

Dear friends: No one yet?

Here I go to null points calculation according with what I posted .

R1: 60.325mm.     R2: 146.05mm      IEC Standard.

First the numerator in the formula:

2 x 60.325 x 146.05 = 17,621

Now the denominator that has two elements.

First one :

1 - 1/1.4142 = 0.2929 x 60.325 = 17.669

Second one:

1 + 1/1.4142 = 1.7071 x 146.05 = 249.32

Now the adds of both:  17.669 + 249.32 = 266.99

Solution:  17,621 / 266.99 =  65.998mm

That's the value of the inner null point in the Löfgren A alignment and coincide with the net calculator for both tonearms EL I posted.

As any can see it needed only most inner/outer groove radius and nothing else.

R.

@rauliruegas 

As any can see it needed only most inner/outer groove radius and nothing else.

This will give you the theoretical placement of the null points.  Nobody is debating this.  Again the topic at hand is actually placing those null points on a record surface and being able to trace through to them with a cartridge.  

More specifically the only comment by me on this topic was simply to state that in order to get existence of two null points, both overhang and offset are required.  In order to calculate those a third variable must be called out (EL, O or P2S).  Using only part of a complete set of formulae "to prove one is right" is of no use in this case.     This has truly become a classic example of what @clearthink outlined above and apologies to all for engaging in this fray of the thread.

dave

Raul, I think you are talking about making a calculation and Dave is talking about geometry.  The point is that in order for any pivoted tonearm to produce two null points on the playing surface of an LP, there MUST be overhang AND the headshell MUST be offset at an angle to the arm wand. You need both conditions.  Simple and true.